2004/12/02 by S. W. Squyres, R. E. Arvidson, J. F. Bell +47 · 7 citations
Physics and Astronomy · #Planetary Science and Exploration #Astro and Planetary Science #Space Science and Extraterrestrial Life
paper · doi:10.1126/science.1106171
openalex publication_date 2004/12/02 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
The Mars Exploration Rover Opportunity has investigated the landing site in Eagle crater and the nearby plains within Meridiani Planum. The soils consist of fine-grained basaltic sand and a surface lag of hematite-rich spherules, spherule fragments, and other granules. Wind ripples are common. Underlying the thin soil layer, and exposed within small impact craters and troughs, are flat-lying sedimentary rocks. These rocks are finely laminated, are rich in sulfur, and contain abundant sulfate salts. Small-scale cross-lamination in some locations provides evidence for deposition in flowing liquid water. We interpret the rocks to be a mixture of chemical and siliciclastic sediments formed by episodic inundation by shallow surface water, followed by evaporation, exposure, and desiccation. Hematite-rich spherules are embedded in the rock and eroding from them. We interpret these spherules to be concretions formed by postdepositional diagenesis, again involving liquid water.